1. Field of the Invention
The present invention relates to an information item selection apparatus whereby selected items of information are supplied to various users in response to respective requests issued by the users.
The term "information" is used herein in a general sense, to include for example audibly reproduced music, speech, still or moving pictures, text, etc. The term "item of information" is used herein .in a broad sense, to include the concept of a single item of a single type of information, such as an audibly reproduced music item (piece of music), and also to include the concept of a specific combination of two or more items of respectively different types of information, for example a predetermined combination of an audibly reproduced music item and an accompanying static or moving picture or text video display.
2. Description of the Prior Art
In the prior art, various types of information item selection apparatus have been envisaged for selecting, from among a large number of stored items of information, specific items that are to be supplied to users in response to requests that are issued by the users. With one type of prior art information item selection apparatus, information items are distributed to a number of information centers and stored therein, and are thereafter supplied from the centers to the users in response to respective requests. An important requirement for an information item selection apparatus in general is that the system should be capable of supplying information items to the users from the centers at high speed, using simple processing (in order to ensure that the system can be implemented at low cost), even under a condition in which a plurality of users are simultaneously inputting requests. However with such a prior art single-layer system, there will be a mixture of information items for which there is a high average frequency of requests from the users, and information items for which there is only a low frequency of requests. Thus it is difficult to execute processing efficiently, to thereby achieve the desired low cost of hardware for implementing the system.. Moreover it is necessary to store large amounts of information at each of the information centers.
One system that has been proposed in the prior art to overcome the above problems, whereby information items can be supplied in accordance with respective requests from a plurality of users, is proposed in Japanese patent Application No. 1-285177. That system has a multi-layer configuration, whereby information items which have the highest frequency of requests from the users are stored in a lowermost layer, the information items having the next-highest frequency of reqest are stored in a next-higher layer, and so on successively, with information items being stored in respective layers of the system in accordance with the frequency of requesting the items. When such a concept is applied to a large-scale information item selection apparatus which is configured with a large number of lower layers, with the number of information items stored in these layers being very large, then processing can be rapidly executed even when requests are received simultaneously from a large number of users. In such conditions, the system is effective. However when such a concept is applied to a system having only a small number of lower layers, where the total volume of information items and the general scale of the system is relatively small, then it becomes difficult to achieve a high speed of response when requests are received simultaneously from a number of different users. In such conditions, the processing efficiency is poor.
Moreover, such a system presents problems with respect to complexity of management. Specifically, when an item increases in popularity, and so has to be transferred to a lower layer of the system, that layer may already be full, in which case it will be necessary to delete from that layer some item which has fallen in popularity (i.e. has a lower frequency of requests). Thus, overall system control becomes complicated, due to the need to manage such transfers between layers and deletions of items.
A second problem which arises with a prior art information item selection apparatus is as follows. One area of application of such information item selection units is that of entertainment. An example of such an entertainment application is a so-called "karaoke" system using a multi-channel information item selection apparatus whereby a number of users can access a central unit, where the term "central unit" as used here signifies an apparatus in which are stored a large number of music items or combined music and video items, and which is responsive to request signals sent from users for transferring selected items to the users. Each of the users is provided with an individual terminal unit which is coupled to receive signals from the central unit. The term "user terminal unit" as used here signifies an apparatus which operates on signals sent from the central unit to provide the item to the user (i.e. to audibly reproduce music items and to display any video items) and which is provided with a switch which can be actuated by the user to issue request signals to the system central unit for desired items. Each terminal unit is also provided with a microphone which is connected to the music reproduction means, so that the user can sing while accompanied by the music (or music and and video items). The video items can include for example the words for a song which is the currently reproduced music item. The video and audio items are usually stored at the system central unit on special compact disks which have both music and video recorded thereon, the combination being sometimes referred to as "Compact Disk Graphics", or CDG, with specific disks being selected, and specific tracks on the disk then selected, by means of a compact disk autochanger apparatus which operates automatically. Thus with such a system, the CDG apparatus of the central unit is used in common by a plurality of users.
In the following, for brevity of description, the term compact disk, or CD will be used as a general term for a compact disk which has only music items recorded thereon and also for a CDG disk having both music and video items recorded thereon, and the term CD autochanger will be used in general for both an autochanger apparatus which is used to play conventional music-only CDs and for an autochanger which is used to play CDG disks.
To minimize the delay in responding to requests that are issued from a number of users simultaneously, with such a prior art "karaoke" system, a plurality of autochanger units can be used in parallel, so that while a compact disk (CD) is being played on one unit the system can be playing one or more other CDs, or loading a CD onto another autochanger unit.
Another type of entertainment application of a information item selection apparatus is that of providing television or other video/audio programs (e.g. shopping information, etc.) to various rooms of a hotel, as requested by the guests.
However with such a system, due to the fact that the facilities of the system central unit are being used in common by a plurality of users, there will frequently occur a condition in which a user issues a request for a particular information item which is currently unavailable, e.g. which is recorded on a CD that is currently being played in response to a previous request from another user. Moreover, even if a number of CD autochangers are operated in parallel at the system central unit there will frequently occur a condition in which no autochanger is currently available to service a request from a user. It is therefore desirable that such a system be provided with means for generating audible and/or visible messages at the user terminal units, to indicate that such a condition has occurred, i.e. to notify the user that there will be a short waiting interval before the request is serviced. It is also desirable to be able to display messages for various other reasons, for example in the case of a "karaoke" system that is installed in a bar or club, messages to notify the users of the closing time and opening time of the establishment, and so on.
One method of generating such messages is to use a voice synthesizer technique, by reading out data stored in a semiconductor memory and converting that to audio form. In the case of messages that are to be displayed visibly at the user terminal units, these can be stored in a video random access memory (RAM), e.g. as sets of mosaic characters, which are read out and supplied to the user terminal units when required. However each of these methods has the disadvantage of providing a much lower degree of audio or video reproduction quality than is normally provided at the user terminal units.
It is not practicable to record such messages on a CD to be played by an autochanger unit when required, since as described above there will be many occasions on which there will be no autochanger currently available.